The present invention relates to a suspension device for motor driven vehicles such as snowmobiles or tractors having an endless track driven by power taken from the vehicle engine by means of a sprocket wheel located on the front portion of the vehicle body, and more particularly to an improved suspension device of a type including a pair of slide rails which are resiliently suspended under the vehicle body to ensure good engagement of the lower or ground-touching face of the endless track with the ground and journal at the rear ends thereof a supporting shaft of idler wheels for the endless track located on the rear portion of the vehicle body.